• Title, Summary, Keyword: dual modules

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A Selective Voltage Balancing Scheme of a Modular Multilevel DC-DC Converter for Solid-State Transformers (반도체 변압기용 모듈형 멀티레벨 DC-DC 컨버터의 선택적인 전압 균형 제어)

  • Lee, Eui-Jae;Kim, Seok-Min;Lee, Kyo-Beum
    • Journal of IKEEE
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    • v.23 no.2
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    • pp.652-658
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    • 2019
  • This paper proposes the selective voltage balancing scheme of a modular multilevel DC-DC converter for solid-state transformers. In general, the sub-module capacitor voltage can be controlled uniformly by individual feedback controllers, however computation time increases according to the number of modules. The voltage balance control scheme in this paper can reduce the computation time by selecting and controlling sub-module of maximum/minimum voltage momentarily. The performance of the proposed selective voltage balancing scheme is verified by simulation.

The Inplementation of Fault-Tolerant Dual System Using the Hot-Standby Sparing Technique (핫 스탠바이 스페어링 기법을 이용한 고장 감내 이중화 시스템 설계)

  • Shin Jin wook;Park Dong sun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.10A
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    • pp.1113-1122
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    • 2004
  • This paper is basically to achieve the high-availability and high-reliability of the control system from the implementation of the fault-tolerant system using the hot-standby sparing technique. To meet the objective, we design and implement a board with fault tolerance I/O bus to detect the fault. Warm-standby sparing technique is the fault tolerance technique usually used for switching control system in present. This technique can be easily implemented, but can not detect the fault quickly and can malfunction because of the hardware fault. The hot-standby sparing fault tolerant technique implemented in this paper is consists of dual processor modules and a I/O processor using fault tolerant I/O bus. The proposed method can find the faults as soon as possible, so it can prevent from wrong operation. Also it is possible to normal re-service due to the short recovering time. To implement the fault-tolerant dual system with fault detection be, two daughter, called FTMA and FTIA, boards designed and implemented are applied to the system. And we also simulated the proposed method to verify the high-availability and high-reliability of the control system using Markov process.

Development of a Small Animal Positron Emission Tomography Using Dual-layer Phoswich Detector and Position Sensitive Photomultiplier Tube: Preliminary Results (두층 섬광결정과 위치민감형광전자증배관을 이용한 소동물 양전자방출단층촬영기 개발: 기초실험 결과)

  • Jeong, Myung-Hwan;Choi, Yong;Chung, Yong-Hyun;Song, Tae-Yong;Jung, Jin-Ho;Hong, Key-Jo;Min, Byung-Jun;Choe, Yearn-Seong;Lee, Kyung-Han;Kim, Byung-Tae
    • The Korean Journal of Nuclear Medicine
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    • v.38 no.5
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    • pp.338-343
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    • 2004
  • Purpose: The purpose of this study was to develop a small animal PET using dual layer phoswich detector to minimize parallax error that degrades spatial resolution at the outer part of field-of-view (FOV). Materials and Methods: A simulation tool GATE (Geant4 Application for Tomographic Emission) was used to derive optimal parameters of small PET, and PET was developed employing the parameters. Lutetium Oxyorthosilicate (LSO) and Lutetium-Yttrium Aluminate-Perovskite(LuYAP) was used to construct dual layer phoswitch crystal. $8{\times}8$ arrays of LSO and LuYAP pixels, $2mm{\times}2mm{\times}8mm$ in size, were coupled to a 64-channel position sensitive photomultiplier tube. The system consisted of 16 detector modules arranged to one ring configuration (ring inner diameter 10 cm, FOV of 8 cm). The data from phoswich detector modules were fed into an ADC board in the data acquisition and preprocessing PC via sockets, decoder block, FPGA board, and bus board. These were linked to the master PC that stored the events data on hard disk. Results: In a preliminary test of the system, reconstructed images were obtained by using a pair of detectors and sensitivity and spatial resolution were measured. Spatial resolution was 2.3 mm FWHM and sensitivity was 10.9 $cps/{\mu}Ci$ at the center of FOV. Conclusion: The radioactivity distribution patterns were accurately represented in sinograms and images obtained by PET with a pair of detectors. These preliminary results indicate that it is promising to develop a high performance small animal PET.

Sender Authentication Mechanism based on DomainKey with SMS for Spam Mail Sending Protection (대량 스팸메일 발송 방지를 위한 SMS 기반 DomainKey 방식의 송신자 인증 기법)

  • Lee, Hyung-Woo
    • The Journal of the Korea Contents Association
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    • v.7 no.4
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    • pp.20-29
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    • 2007
  • Although E-mail system is considered as a most important communication media, 'Spam' is flooding the Internet with many copies of the same message, in an attempt to force the message on people who would not otherwise choose to receive it. Most spam is commercial advertising, often for dubious products, get-rich-quick schemes, or quasi-legal services. Therefore advanced anti-spam techniques are required to basically reduce its transmission volume on sender mail server or MTA, etc. In this study, we propose a new sender authentication model with encryption function based on modified DomainKey with SMS for Spam mail protection. From the SMS message, we can get secret information used for verification of its real sender on e-mail message. And by distributing this secret information with SMS like out-of-band channel, we can also combine proposed modules with existing PGP scheme for secure e-mail generation and authentication steps. Proposed scheme provide enhanced authentication function and security on Spam mail protection function because it is a 'dual mode' authentication mechanism.

A Study on the Modularity in Clothing Design (의복디자인에서의 모듈성에 대한 연구)

  • Lim, So-Yon;Lee, Joo-Hyeon
    • Journal of the Korea Fashion and Costume Design Association
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    • v.14 no.2
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    • pp.1-10
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    • 2012
  • Clothing design is one of design products for human, the end user and corresponds to artifacts. Sometimes artifacts with one mono module exist, and so does artifacts assembled and combined with multi modules of same shape and size or various shapes and sizes and thus all design products can be understood by modularity concept. The purpose of this study was to make a new suggestion for the clothing design and production of high uniqueness and creativity by reviewing and synthesizing the foundation of clothing modularity concept as the original clothing design figures from the history have shown various modularity concept evolution from mono module to multi module stages. The methods of this study were to identify clothing modularity and analyze the type, evolving direction, and category of clothing modularity, and the value of clothing modularization design through comprehensive literature reviews on topic-related books and theses. The original clothing figures with Significance from the clothing history were analyzed in evolution sequence for application direction and value of clothing modularity in flat pattern. Clothing modularity in ancient clothing figures was classified as three types of the fixed, drapery, and straight lined in evolving direction from clothing of mono module to flat patterned clothing. The direction of clothing modularity was identified as mono- dual-triple-multi into another level of multi modularity after intentional devolution. The categorization of clothing modularity was identified in terms of clothing flat construction, clothing design construction, and clothing form modeling. The value of clothing modularization design using clothing modularity was identified as economical efficiency, convenience, promptitude, adaptability, functionality, and creativity.

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A Study on CSS3 Stylesheet Extension and Emulator for Representation of Stereo Web Content in 3DTV (3DTV에서 스테레오 웹 콘텐츠 표현을 위한 CSS3 사양 확장 및 에뮬레이터 연구)

  • Lee, Hee-Jin;Yim, Hyun-Jeong;Lim, Soon-Bum
    • Journal of the Korea Computer Graphics Society
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    • v.19 no.4
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    • pp.1-11
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    • 2013
  • In this paper, we represented the HTML5 webpage in 3D space for the 3D stereoscopic display by using CSS3 stylesheet; browser-based declarative contents, and proposed CSS Stereo 3DTV Profile. First, we suggested various webpage separation methods for reconstructing webpages in the 3D space effectively. Next, we suggested 3D view volume setting method by using extended CSS3 modules. And then, pre-processor converts sample contents which is written extended CSS stylesheet into the present CSS stylesheet for displaying in the webkit based browser. For the resulting stereoscopic images, we developed a rendering engine emulator which is implemented in JavaScript for simple display in the web browser, which produced dual images from virtual left and right-eyed cameras. And we have checked the sample contents displayed on the 3DTV.

Development of New Photogrammetric Software for High Quality Geo-Products and Its Performance Assessment

  • Jeong, Jae-Hoon;Lee, Tae-Yoon;Rhee, Soo-Ahm;Kim, Hyeon;Kim, Tae-Jung
    • Korean Journal of Remote Sensing
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    • v.28 no.3
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    • pp.319-327
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    • 2012
  • In this paper, we introduce a newly developed photogrammetric software for automatic generation of high quality geo-products and its performance assessment carried out using various satellite images. Our newly developed software provides the latest techniques of an optimized sensor modelling, ortho-image generation and automated Digital Elevation Model (DEM) generation for diverse remote sensing images. In particular, images from dual- and multi-sensor images can be integrated for 3D mapping. This can be a novel innovation toward a wider applicability of remote sensing data, since 3D mapping has been limited within only single-sensor so far. We used Kompsat-2, Ikonos, QuickBird, Spot-5 high resolution satellite images to test an accuracy of 3D points and ortho-image generated by the software. Outputs were assessed by comparing reliable reference data. From various sensor combinations 3D mapping were implemented and their accuracy was evaluated using independent check points. Model accuracy of 1~2 pixels or better was achieved regardless of sensor combination type. The high resolution ortho-image results are consistent with the reference map on a scale of 1:5,000 after being rectified by the software and an accuracy of 1~2 pixels could be achieved through quantitative assessment. The developed software offers efficient critical geo-processing modules of various remote sensing images and it is expected that the software can be widely used to meet the demand on the high-quality geo products.

Implementation of VLC Relay Module to Improve Communication Disconnection Phenomenon and Coverage Expansion in Non-Line-of-Sight Area (비가시선 영역의 통신 단절 현상 개선과 커버리지 확장을 위한 VLC 릴레이 모듈 구현)

  • Lee, Sang-gwon;Lee, Dae-hee;Oh, Chang-heon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.22 no.1
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    • pp.140-146
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    • 2018
  • Recently, VLC(Visible Light Communication) fusing with LED(Light Emitting Diode) used in indoor lighting and wireless communication technology has attracted attention. However, the VLC can communicate only within the coverage to measure the optical signal and the communication disconnection phenomenon is occur in the NLoS(Non-Line-of-Sight) area. In this paper, we propose VLC relay module to extend the coverage of VLC and improve the communication disconnection phenomenon in NLoS area. The proposed VLC relay module transmits the packet received from the transmitter to the VLC relay module and receiver. The experiment was carried out by installing one VLC transmitter and three VLC relay modules, communication coverage expansion and the improvement of communication disconnection phenomenon in the NLoS were confirmed by the increase of the VLC relay module. Also, we confirmed that the optical signal measurement performance is improved 2.4 times by using the dual sampling method.

Nano-scale Patterning on Diamond substrates using an FIB (FIB를 이용한 다이아몬드 기판 위의 나노급 미세 패턴의 형상 가공)

  • Song, Oh-Sung;Kim, Jong-Ryul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.7 no.6
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    • pp.1047-1055
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    • 2006
  • We patterned nano-width lines on a super hard bulk diamond substrate by varying the ion beam current and ion beam sources with a dual beam field ion beam (FIB). In addition, we successfully fabricated two-dimensional nano patterns and three-dimensional nano plate modules. We prepared nano lines on a diamond and a silicon substrate at the beam condition of 30 kV, 10 pA $\sim$ 5 nA with $Ga^+$ ion and $H_2O$ assisted ion sources. We measured each of the line-width, line-depth, etched line profiles, etch rate, and aspect ratio, and then compared them. We confirmed that nano patterning was possible on both a bulk diamond and a silicon substrate. The etch rate of $H_2O$ source can be enhanced about two times than that of Ga source. The width of patterns on a diamond was smaller than that on a silicon substrate at the same ion beam power The sub-100 nm patterns on a diamond were made under the charge neutralization mode to prevent charge accumulation. We successfully made a two-dimensional, 240 nm-width text of the 300-lettered Lord's Prayer on a gem diamond with 30 kV-30 pA FIB. The patterned text image was readable with a scanning electron microscope. Moreover, three dimensional nano-thick plate module fabrication was made successfully with an FIB and a platinum deposition, and electron energy loss spectrum (EELS) analysis was easily performed with the prepared nano plate module.

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A Design and Fabrication of the X-Band Transmit/Receive Module for Active Phased Array SAR Antennas (능동 위상 배열 SAR 안테나를 위한 X-대역 송수신 모듈의 설계 및 제작)

  • Chong, Min-Kil;Kim, Sang-Keun;Na, Hyung-Gi;Lee, Jong-Hwan;Yi, Dong-Woo;Baik, Seung-Hun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.10
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    • pp.1050-1060
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    • 2009
  • In this paper, a X-Band T/R-module for SAR(Synthetic Aperture Radar) systems based on active phased array antennas is designed and fabricated. The T/R modules have a and width of more than 800 MHz centered at X-Band and support dual, switched polarizations. The output power of the module is 7 watts over a wide bandwidth. The noise figure is as low as 3.9 dB. Phase and amplitude are controlled by a 6-bit phase shifter and a 6-bit digital attenuator, respectively. Further the fabricated T/R module has est and calibration port with directional coupler and power divider. Highly integrated T/R module is achieved by using LTCC(Low Temperature Co-fired Ceramic) multiple layer substrate. RMS gain error is less than 0.8 dB max. in Rx mode, and RMS phase error is less than $4^{\circ}$ max. in Rx/Tx phase under all operating frequency band, or the T/R module meet the required electrical performance m test. This structure an be applied to active phase array SAR Antennas.